Performance modeling of networked control systems

Analysis of Distributed Real-Time Control Systems with Shared Network Infrastructures

“…1. Our distributed control functionalities are belonging to Layer 7 which can, in principle, be placed on top of any of the above layers as, e.g., a pure hardware solution directly across wires of the PHY Layer 1 for signal transmissions as in classical electrical control systems, the MAC Layer 2a of shared LANs for frame exchanges, the Link Layer 2b for safe exchange of frames as in our paper [14,15], the Network Layer 3 for an unreliable end-to-end exchange of packets (but with enhanced transport options), or the Transport Layer 4 for a safe exchange of byte streams endto-end. The functional support increases in the upward direction but the end-to-end delays increase accordingly.…”

“…The model of Fig. 4 has been analyzed before [14] with a dedicated network infrastructure where the "Network" is a two-way logical link control (LLC) connection (Layer 2b) operated under control of the "Send-and-Wait" or under the "Selected Repeat" protocol with Timeout recovery in case of frame loss or excessive frame delay between A and C and between C and A separately. In this contribution we extend the model to a NCS with a shared network infrastructure, i.e., a local area network operated on layers 1 (Physical Layer) and 2a (Media Access Control Layer) by a wiredor a wireless network.…”

“…The discrete time state control theory is based on detailed system state variables and their description by systems of state equations and using, e.g., the MAT-LAB Simulink tool or a computational solution of matrix equation systems. We have applied these method in [14]. The aggregated arrival process of requests of all stations is assumed to follow a Poisson process, i.e., the inter-arrival times are negative-exponentially distributed (Type M).…”

“…Typically, control and network analyses are treated independently; this paper attempts at an integrated multi-layer analysis approach by aggregating the complete network infrastructure into a stochastic equivalent phase which is inserted in the specific application control layer. In a first paper [14] we have studied a single Networked Control System where the whole functionality of the underlying network is aggregated into a functional module operated on the Link Layer (2b) with acknowledgment signaling and Timeout control for each frame.…”